[Elasticsearch](http://www.elasticsearch.org/) is the default metadata store for
PredictionIO. Download and extract it.

```
$ wget https://download.elasticsearch.org/elasticsearch/elasticsearch/<%= data.versions.elasticsearch_download_filename %>.tar.gz
$ tar zxvfC <%= data.versions.elasticsearch_download_filename %>.tar.gz PredictionIO-<%= data.versions.pio %>/vendors
```

INFO: If you decide to install Elasticsearch to another location, you must edit
`PredictionIO-<%= data.versions.pio %>/conf/pio-env.sh` and change the
`PIO_STORAGE_SOURCES_ELASTICSEARCH_HOME` variable to point to your own
Elasticsearch installation.

INFO: If you are using a shared network, change the `network.host` line in
`PredictionIO-<%= data.versions.pio %>/vendors/<%=
data.versions.elasticsearch_download_filename %>/config/elasticsearch.yml` to
`network.host: 127.0.0.1` because by default, Elasticsearch looks for other
machines on the network upon setup and you may run into weird errors if there
are other machines that is also running Elasticsearch.

If you are not using the default setting at `localhost`, you may change the
following in `PredictionIO-<%= data.versions.pio %>/conf/pio-env.sh` to fit your
setup.

```
PIO_STORAGE_SOURCES_ELASTICSEARCH_TYPE=elasticsearch
PIO_STORAGE_SOURCES_ELASTICSEARCH_HOSTS=localhost
PIO_STORAGE_SOURCES_ELASTICSEARCH_PORTS=9300
```
